★ 两种单位制使用相同的颜色分级。分级按物理量设定一次，只更换标签，因此 25 mm 显示为 0.98 in 而非整数。相同的颜色始终代表相同的数值，两种单位制的地图可以并排比较。
12 · Vector layers
Analyze › Vector layers splits lines, units, labels and charts into separate layers. There is no limit on how many.
◉ / ○ show or hide that layer
🔒 lock — nothing is drawn there
Opacity for that layer only
↑ ↓ reorder — later layers draw on top
Clip shows the layer only inside one faction's territory
Double-click the name to rename it
★ Painting is not split. Holding several 10.5-million-cell arrays would double the memory. Only lines and points are split.
13 · Colour by rules
Below Analyze › Select by attribute there is a Rules box. Store several rules — "0–500 m green, 501–1500 m yellow" — and paint them in one go.
+ Add rule stores one rule with the current palette colour
▶ Run rules paints them in order — later rules cover earlier ones
▤ Smooth ramp blends between two colours instead of steps
★ Water is skipped. It can be undone.
14 · Saving
Autosave is on. When you stop working it is stored in the browser, and next time you are asked whether to continue from there.
There are several places to keep things, so here is what each one is.
Save my work (.json) — real safekeeping. A file with drawing, lines, units, layers and bookmarks
Autosave — this browser and device only
Keep for later › Keep this work in the browser — the same store, done by hand
Snapshots — keep the current drawing and show it underneath as tracing (five slots)
Bookmark › this place — keeps only where you are looking
Bookmark › this base map + layers — keeps the base map and which layers are on. Not the drawing
Preset › selection · unit settings — keeps settings to reuse
Link — puts the work in the address. If it is too big, save a file instead
★ Autosave lives only in this browser on this device. For real safekeeping use Save map (.json). The file holds not only your drawing but the map state you were looking at — projection, base layer, zoom, camera and year.